just had new piston n rings put on . still have a problem with back fire and bogs down . idles great .!.My question is would a crankcase leak cause this ? that would give me the bad compression ? no .I have nothing leaking under the motor so im leaning towards an electrical prob ..like I said idles great .. spits n sputters given throttle .not a carb problem..not a bad rings prob..thanks.

 

Check the end of the pipe. The screen gets plugged.
A seal leak has nothing to do with compression.

 

negative ..the spark arrester is out .I have a new piston /rings .top end is new. on a 2 stroke if the bottom end is leaking it will suck in air ? I will look into cdi box.. But another $140 is killing me. guessing is not an option .

 

Aleaking seal can suck air in.
Is there spark? Find the specs and ohm the coil if need be.

 

update !! just did another compression test on a New ! piston /ring / cylinderhead.. Its still leaking pressure so I am sure its in the crankcase . anyone take an eton 90 2004 2 stroke crank case apart ? I have new LH seals coming in the mail.. was told they are the easier ones to change first .

 

Let's get this straight...
Are you doing a compression test or a crankcase leakdown test (which isn't done with a comp tester)?

If you are doing a compression test, your gauge is leaking.

Ummm...the main bearing crankcase seals are on the outside of the case....The LH are easier. It's under/behind the front clutch.
The RH you would need to pull the stator off.

 

so you have spark?

 

[QUOTE=LT80;3304346]Let's get this straight...
Are you doing a compression test or a crankcase leakdown test (which isn't done with a comp tester)?

If you are doing a compression test, your gauge is leaking.

Ummm...the main bearing crankcase seals are on the outside of the case....The LH are easier. It's under/behind the front clutch.
The RH you would need to pull the stator off.[/QUOT

Ok never gave that a thought . My compression tester is leaking .. it is old. So let's start again. I have new piston / rings . I have the spark arrested out and verified the exhaust is clear.. quad idles great . Starts right up. Won't run well at all backfires. Spits out the air cleaner.ect.. like its out of time. Cleaned out the carb. / jets 3 times just to be safe. I don't think it's electrical because it sits running with no problem.. thanks..

 

I agree, let's not think electrical at this point.
How about a cracked reed?

 

The reeds are metal? In an eton. No?